Systems And Methods For Unobstructed Visualization And Ablation

ABSTRACT

Systems and methods for unobstructed visualization and ablation, particularly of the pulmonary veins, are described herein. Such a system may include a deployment catheter and an attached imaging hood deployable into an expanded configuration as well as one or more expandable anchors which are temporarily securable within a respective pulmonary vein while allowing blood flow to pass through the anchor unimpeded. With the one or more non-impeding anchors secured within a respective pulmonary vein, ablation of the tissue surrounding the ostium or several ostia may be effected with the catheter while the tissue is under direct visualization.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Prov. Pat. App. 60/870,598 filed Dec. 18, 2006, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to medical devices used for accessing, visualizing, and/or treating regions of tissue within a body. More particularly, the present invention relates to methods and apparatus for intravascularly accessing, visualizing, and/or treating tissue regions at or around the ostia of the pulmonary veins of the heart without obstructing blood flow from the pulmonary vein.

BACKGROUND OF THE INVENTION

Conventional devices for accessing and visualizing interior regions of a body lumen are known. For example, ultrasound devices have been used to produce images from within a body in vivo. Ultrasound has been used both with and without contrast agents, which typically enhance ultrasound-derived images.

Other conventional methods have utilized catheters or probes having position sensors deployed within the body lumen, such as the interior of a cardiac chamber. These types of positional sensors are typically used to determine the movement of a cardiac tissue surface or the electrical activity within the cardiac tissue. When a sufficient number of points have been sampled by the sensors, a “map” of the cardiac tissue may be generated.

Another conventional device utilizes an inflatable balloon which is typically introduced intravascularly in a deflated state aid then inflated against the tissue region to be examined. Imaging is typically accomplished by an optical fiber or other apparatus such as electronic chips for viewing the tissue through the membrane(s) of the inflated balloon. Moreover, the balloon must generally be inflated for imaging. Other conventional balloons utilize a cavity or depression formed at a distal end of the inflated balloon. This cavity or depression is pressed against the tissue to be examined and is flushed with a clear fluid to provide a clear pathway through the blood.

However, such imaging balloons have many inherent disadvantages. For instance, such balloons generally require that the balloon be inflated to a relatively large size which may undesirably displace surrounding tissue and interfere with tine positioning of the imaging system against the tissue. Moreover, the working area created by such inflatable balloons are generally cramped and limited in size. Furthermore, inflated balloons may be susceptible to pressure changes in the surrounding fluid. For example, if the environment surrounding the inflated balloon undergoes pressure changes, e.g., during systolic and diastolic pressure cycles in a beating heart, the constant pressure change may affect the inflated balloon volume audits positioning to produce unsteady or undesirable conditions for optimal tissue imaging.

Accordingly, these types of imaging modalities are generally unable to provide desirable images useful for sufficient diagnosis and therapy of the endoluminal structure, due in part to factors such as dynamic forces generated by the natural movement of the heart. Moreover, anatomic structures within the body can occlude or obstruct the image acquisition process. Also, the presence and movement of opaque bodily fluids such as blood generally make in vivo imaging of tissue regions within the heart difficult.

Other external imaging modalities are also conventionally utilized. For example, computed tomography (CT) and magnetic resonance imaging (MRI) are typical modalities which are widely used to obtain images of body lumens such as the interior chambers of the heart. However, such imaging modalities fail to provide real-time imaging for intra-operative therapeutic procedures. Fluoroscopic imaging, for instance, is widely used to identity anatomic landmarks within the heart and other regions of the body. However, fluoroscopy fails to provide an accurate image of the tissue quality or surface and also fails to provide for instrumentation for performing tissue manipulation or other therapeutic procedures upon the visualized tissue regions. In addition, fluoroscopy provides a shadow of the intervening tissue onto a plate or sensor when it may be desirable to view the intraluminal surface of the tissue to diagnose pathologies or to perform some form of therapy on it.

Moreover, many of the conventional imaging systems lack the capability to provide therapeutic treatments or are difficult to manipulate in providing effective therapies, For instance, the treatment in a patient's heart for atrial fibrillation is generally made difficult by a number of-factors, such as visualization of the target tissue, access to the target tissue, and instrument articulation and management, amongst others,

Conventional catheter techniques and devices, tor example such as those described in U.S. Pat. Nos. 5,895,417; 5,941,845; and 6,129,724, used on the epicardial surface of the heart may be difficult in assuring a transmural lesion or complete blockage of electrical signals. In addition, current devices may have difficulty dealing with varying thickness of tissue through which a transmural lesion desired.

Conventional accompanying imaging devices, such as fluoroscopy, are unable to detect perpendicular electrode orientation, catheter movement during the cardiac cycle, and image catheter position throughout lesion formation. Without real-time visualization, it is difficult to reposition devices to another area that requires transmural lesion ablation. The absence of real-time visualization also poses the risk of incorrect placement and ablation of critical structures such as sinus node tissue which can lead to fatal consequences.

Thus, a tissue imaging system which is able to provide real-time in vivo access to and images of tissue regions within body lumens such as the heart through opaque media such as blood and which also provides instruments for therapeutic procedures such as ablation of the ostia around the pulmonary veins are desirable.

SUMMARY OF THE INVENTION

A tissue imaging and manipulation apparatus that may be utilized for procedures within a body lumen, such as the heart, in which visualization of the surrounding tissue is made difficult, if not impossible, by medium contained within the lumen such as blood, is described below. Generally, such a tissue imaging and manipulation apparatus comprises an optional delivery catheter or sheath through which a deployment catheter and imaging hood may be advanced for placement against or adjacent to the tissue to be imaged.

The deployment catheter may define a fluid delivery lumen therethrough as well as an imaging lumen within which an optical imaging fiber or electronic imaging assembly may be disposed for imaging tissue. When deployed, the imaging hood may be expanded into any number of shapes, e.g., cylindrical, conical semi-spherical, etc., provided that an open area or field is defined by the imaging hood. The open area is the area within which the tissue region of interest may be imaged and which, is also defined in part by the contacted tissue region as well. The imaging hood may also define an atraumatic contact lip or edge for placement or abutment against the tissue region of interest. Moreover, the distal end of the deployment catheter or separate manipulatable catheters may be articulated through various controlling mechanisms such as push-pull wires manually or via computer control

The deployment catheter may also be stabilized relative to the tissue surface through various methods. For instance, inflatable stabilizing balloons positioned along a length of the catheter may be utilized, or tissue engagement anchors may be passed through or along the deployment catheter for temporary engagement of the underlying tissue.

In operation, after the imaging hood has been deployed, fluid may be pumped at a positive pressure through the fluid delivery lumen until the fluid fills the open area completely and displaces any blood from within the open area. The fluid may comprise any biocompatible fluid, e.g., saline, water, plasma, Fluofinert™, etc., which is sufficiently transparent to allow for relatively undistorted visualization through the fluid. The fluid may be pumped continuously or intermittently to allow for image capture by an optional processor which may be in communication with the assembly.

The imaging hood, may be formed into any number of configurations and the imaging assembly may also be utilized with any number of therapeutic tools, such as tissue ablation instruments, which may be deployed through the deployment catheter. One particular variation may employ an imaging hood having a tissue anchor deployable therethrough and into a portion of a body lumen such as the pulmonary vein. Once the anchor has been temporarily deployed and secured within the pulmonary vein, the hood aid ablation instrument may be articulated around a circumference of the vein ostium or several ostia where the tissue may be ablated in a controlled and consistent manner to electrically isolate the tissue such that a conduction block is created.

While the imaging hood is moved around the tissue with the anchor deployed and secured distally within the pulmonary vein, the imaging hood may be articulated such that blood flow through the pulmonary vein is unobstructed or uninhibited by the hood.

The tissue surrounding the ostium may be visualized via the imaging hood prior to, during, or after the ablation to ensure that the appropriate tissue is suitably ablated for treating conditions such as atrial fibrillation. The distally located anchor which secures a relative position of the imaging hood with respect to the tissue may he maintained until the procedure is completed. After completion, the anchor may be at least partially withdrawn into the imaging hood or reconfigured into a low-profile shape to disengage the tissue and allow the imaging hood to be removed or repositioned in the patient body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side view of one variation of a tissue imaging apparatus during deployment from a sheath or delivery catheter.

FIG. 1B shows the deployed tissue imaging apparatus of FIG. 1A having an optionally expandable hood or sheath attached to an imaging and/or diagnostic catheter.

FIG. 1C shows an end view of a deployed imaging apparatus.

FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an additional lumen, e.g., for passage of a guidewire therethrough.

FIGS. 2A and 2B show one example of a deployed tissue imager positioned against or adjacent to the tissue to be imaged and a flow of fluid, such as saline, displacing blood from within the expandable hood.

FIG. 3A shows an articulatable imaging assembly which may be manipulated via push-pull wires or by computer control.

FIGS. 3B and 3C show steerable instruments, respectively, where an articulatable delivery catheter maybe steered within the imaging hood or a distal portion of the deployment catheter itself may be steered.

FIGS. 4A to 4C show side and cross-sectional end views, respectively, of another variation having an off-axis imaging capability.

FIGS. 4D and 4E show examples of various visualization imagers which may be utilized within or along the imaging hood.

FIG. 5 shows an illustrative view of an example of a tissue imager advanced intravascularly within a heart for imaging tissue regions within an atrial chamber.

FIGS. 6A to 6C illustrate deployment catheters having one or more optional inflatable balloons or anchors for stabilizing the device during a procedure.

FIGS. 7A and 7B illustrate a variation of an anchoring mechanism such as a helical tissue piercing device for temporarily stabilizing the imaging hood relative to a tissue surface.

FIG. 7C shows another variation for anchoring the imaging hood having one or more tubular support members integrated with the imaging hood; each support members may define a lumen therethrough for advancing a helical tissue anchor within.

FIG. 8A shows an illustrative example of one variation of how a tissue imager may be utilized with an imaging device.

FIG. 8B shows a further illustration of a hand-held variation of the fluid delivery and tissue manipulation system.

FIGS. 9A to 9C illustrate an example of capturing several images of the tissue at multiple regions.

FIGS. 10A and 10B show charts illustrating how fluid pressure within the imaging hood may be coordinated with the surrounding blood pressure; the fluid pressure in the imaging hood may be coordinated with the blood pressure or it may be regulated based upon pressure feedback from the blood.

FIGS. 11A and 11B show side and end views, respectively, of a hood and catheter engaging and visualizing the pulmonary vein ostium while temporarily tethered via a deployable anchor positioned within the pulmonary vein such that blood flow through the pulmonary vein is unobstructed.

FIGS. 12A and 12B show side and end views, respectively, of the hood and catheter articulated around the pulmonary vein ostium while ablating and/or visualizing the underlying tissue.

FIGS. 13A to 13C show end views of the device with the pulmonary vein anchor acting as a guide to ensure hood stability while the hood is articulated circumferentially along the pulmonary vein ostium, while leaving the blood flow through the ostium unimpeded.

FIGS. 14A and 14B show partial cross-sectional side views of a helical anchor constrained in its low-profile configuration within a cylindrical sheath and deployed in its expanded and unconstrained configuration.

FIG. 14C shows a partial cross-sectional side view of the helical anchor temporarily secured within the pulmonary vein while allowing for blood flow through the vessel to continue unimpeded or unobstructed.

FIGS. 15A and 15B show partial cross-sectional side views of a basket anchor constrained in its low-profile configuration within a cylindrical sheath and deployed in its expanded and unconstrained configuration.

FIG. 15C shows a partial cross-sectional side view of the basket anchor temporarily secured within the pulmonary vein while allowing for blood flow through the vessel to continue unimpeded or unobstructed.

FIGS. 16A and 16B show partial cross-sectional side views of a mesh anchor constrained in its low-profile configuration within a cylindrical sheath and deployed in its expanded and unconstrained configuration.

FIG. 16C shows a partial cross-sectional side view of the mesh anchor temporarily secured within the pulmonary vein while allowing for blood flow through the vessel to continue unimpeded or unobstructed.

FIGS. 17A and 17B show side views of an inflatable balloon anchor assembly in its low profile configuration and its inflated configuration, respectively, where the assembly is expandable into a staggered configuration such that blood may still flow unobstructed past the inflated balloons.

FIGS. 18A and 18B show a variation of the tissue visualization catheter having a reconfigurable flap which is configured to pivot about the contact lip or edge of the hood from its low profile configuration to its extended configuration, respectively.

FIGS. 19A and 19B show perspective views of the device of FIGS. 18A and 18B with the flap shown in its low profile and extended configurations, respectively.

FIG. 20 shows a side view of the hood having the flap deployed and engaged along the PV ostium, to act as a guide for articulating the hood circumferentially.

FIGS. 21A to 21C show end views of the catheter and hood having the deployed flap engaged along the pulmonary vein ostium such that the blood flow through the vessel is unimpeded while circumferentially ablating the underlying tissue under direct visualization.

FIG. 22 shows a perspective view of another variation having an anchor extending from a side port for deployment within the vessel lumen.

FIGS. 23A and 23B show perspective and end views, respectively, of the anchor engaged within a first pulmonary vein while the tissue around adjacent ostia are ablated in an encircling lesion to electrically isolate the vessels.

DETAILED DESCRIPTION OF THE INVENTION

A tissue-imaging and manipulation apparatus described below is able to provide real-time images in vivo of tissue regions within a body lumen such as a heart, which is filled with blood flowing dynamically therethrough and is also able to provide intravascular tools and instruments for performing various procedures upon the imaged tissue regions. Such an apparatus may be utilized for many procedures, e.g., facilitating transseptal access to the left atrium, cannulating the coronary sinus, diagnosis of valve regurgitation/stenosis, valvuloplasty, atrial appendage closure, arrhythmogenic focus ablation, among other procedures. Further examples of tissue visualization catheters which may be utilized are shown and described in further detail in U.S. patent application Ser. No. 11/259,498 filed Oct. 25, 2005, which has been incorporated hereinabove by reference in its entirety.

One variation of a tissue access and imaging apparatus is shown in the detail perspective views of FIGS. 1A to 1C. As shown in FIG. 1A, tissue imaging and manipulation assembly 10 may be delivered intravascularly through the patient's body in a low-profile configuration via a delivery catheter or sheath 14. In the case of treating tissue, such as the mitral valve located at the outflow tract of the left atrium of the heart, it is generally desirable to enter or access the left atrium while minimizing trauma to the patient. To non-operatively effect such access, one conventional approach involves puncturing the intra-atrial septum from the right atrial chamber to the left atrial chamber in a procedure commonly called a transseptal procedure or septostomy. For procedures such as percutaneous valve repair and replacement, transseptal access to the left atrial chamber of the heart may allow for larger devices to be introduced into the venous system than can generally be introduced percutaneously into the arterial system.

When the imaging and manipulation assembly 10 is ready to be utilized for imaging tissue, imaging hood 12 may be advanced relative to catheter 14 and deployed from a distal opening of catheter 14, as shown by the arrow. Upon deployment, imaging hood 12 may be unconstrained to expand or open into a deployed imaging configuration, as shown in FIG. 1B. Imaging hood 12 may be fabricated from a variety of pliable or conformable biocompatible material including but not limited to, e.g., polymeric, plastic, or woven materials. One example of a woven material is Kevlar® (E. I. du Pont de Nemours, Wilmington, Del.) which is an aramid and which can be made into thin, e.g., less than 0.001 in., materials which maintain enough integrity for such applications described herein. Moreover, the imaging hood 12 may be fabricated from a translucent or opaque material and in a variety of different colors to optimize or attenuate any reflected lighting from surrounding fluids or structures, i.e., anatomical or mechanical structures or instruments. In either case, imaging hood 12 may be fabricated into a uniform structure or a scaffold-supported structure, in which case a scaffold made of a shape memory alloy, such as Nitinol, or a spring steel, or plastic, etc., may he fabricated and covered with the polymeric, plastic, or woven material. Hence, imaging hood 12 may comprise any of a wide variety of barriers or membrane structures, as may generally be used to localize displacement of blood or the like from a selected volume of a body lumen or heart chamber. In exemplary embodiments, a volume within an inner surface 13 of imaging hood 12 will be significantly less than a volume of the hood 12 between inner surface 13 and outer surface 11.

Imaging hood 12 may be attached at interface 24 to a deployment catheter 16 which may be translated independently of deployment catheter or sheath 14. Attachment of interface 24 may be accomplished through any number of conventional methods. Deployment catheter 16 may define a fluid delivery lumen 18 as well as an imaging lumen 20 within which an optical imaging fiber or assembly may be disposed for imaging tissue. When deployed, imaging hood 12 may expand into any number of shapes, e.g., cylindrical, conical as shown, semi-spherical etc., provided that an open area or field 26 is defined by imaging hood 12. The open area 26 is the area within which the tissue region of interest may be imaged. Imaging hood 12 may also define an atraumatic contact lip or edge 22 for placement or abutment against the tissue region of interest. Moreover, the diameter of imaging hood 12 at its maximum fully deployed diameter, e.g., at contact lip or edge 22, is typically greater relative to a diameter of the deployment catheter 16 (although a diameter of contact lip or edge 22 may be made to have a smaller or equal diameter of deployment catheter 16). For instance, the contact edge diameter may range anywhere from 1 to 5 times (or even greater, as practicable) a diameter of deployment catheter 16. FIG. 1C shows an end view of the imaging hood 12 in its deployed configuration. Also shown are the contact lip or edge 22 and fluid delivery lumen 18 and imaging lumen 20.

The imaging and manipulation assembly 10 may additionally define a guidewire lumen therethrough, e.g., a concentric or eccentric lumen, as shown in the side and end views, respectively, of FIGS. 1D to 1F. The deployment catheter 16 may define guidewire lumen 19 for facilitating the passage of the system over or along a guidewire 17, which may be advanced intravascularly within a body lumen. The deployment catheter 16 may then be advanced over the guidewire 17, as generally known in the art.

In operation, after imaging hood 12 has been deployed, as in FIG. 1B, and desirably positioned against the tissue region to be imaged along contact edge 22, the displacing fluid may be pumped at positive pressure through fluid delivery lumen 18 until the fluid fills open area 26 completely and displaces any fluid 28 from within open area 26. The displacing fluid flow may be laminarized to improve its clearing effect and to help prevent blood from re-entering the imaging hood 12. Alternatively, fluid flow may be started before the deployment lakes place. The displacing fluid, also described herein as imaging fluid, may comprise any biocompatible fluid, e.g., saline, water, plasma, etc., which is sufficiently transparent to allow for relatively undistorted visualization through the fluid. Alternatively or additionally, any number of therapeutic drugs may be suspended within the fluid or may comprise the fluid itself which is pumped into open area 26 and which is subsequently passed into and through the heart and the patient body.

As seen in the example of FIGS. 2A and 2B, deployment catheter 16 may be manipulated to position deployed imaging hood 12 against or near the underlying tissue region of interest to be imaged, in this example a portion of annulus A of mitral valve MV within the left atrial chamber. As the surrounding blood 30 flows around imaging hood 12 and within open area 26 defined within imaging hood 12, as seen in FIG. 2A, the underlying annulus A is obstructed by the opaque blood 30 and is difficult to view through the imaging lumen 20. The translucent fluid 28, such as saline, may then be pumped through fluid delivery lumen 18, intermittently or continuously, until the blood 30 is at least partially, and preferably completely, displaced from within open area 26 by fluid 28, as shown in FIG. 2B.

Although contact edge 22 need not directly contact the underlying tissue, it is at least preferably brought into close proximity to the tissue such that the flow of clear fluid 28 from open area 26 may be maintained to inhibit significant backflow of blood 30 back into open area 26. Contact edge 22 may also be made of a soft elastomeric material such-as certain soft grades of silicone or polyurethane, as typically known, to help contact edge 22 conform to an uneven or rough underlying anatomical tissue surface. Once the blood 30 has been displaced from imaging hood 12, an image may then be viewed of the underlying tissue through the clear fluid 30. This image may then be recorded or available for real-time viewing for performing a therapeutic procedure. The positive flow of fluid 28 may be maintained continuously to provide for clear viewing of the underlying tissue. Alternatively, the fluid 28 may be pumped temporarily or sporadically only until a clear view of the tissue is available to be imaged and recorded, at which point the fluid flow 28 may cease and blood 30 may be allowed to seep or flow back, into imaging hood 12. This process may be repeated a number of times at the same tissue region or at multiple tissue regions.

In desirably positioning the assembly at various regions within the patient body, a number of articulation and manipulation controls may be utilized. For example, as shown in the articulatable imaging assembly 40 in FIG. 3A, one or more push-pull wires 42 may be routed through deployment catheter 16 for steering the distal end portion of the device in various directions 46 to desirably position the imaging hood 12 adjacent to a region of tissue to be visualized. Depending upon the positioning and the number of push-pull wires 42 utilized, deployment catheter 16 and imaging hood 12 may be articulated into any number of configurations 44. The push-pull wire or wires 42 may be articulated via their proximal ends from outside the patient body manually utilizing one or more controls. Alternatively, deployment catheter 16 may be articulated by computer control, as further described below.

Additionally or alternatively, an articulatable delivery catheter 48, which may be articulated via one or more push-pull wires and having an imaging lumen and one or more working lumens, may be delivered through the deployment catheter 16 and into imaging hood 12. With a distal portion of articulatable delivery catheter 48 within imaging hood 12, the clear displacing fluid may be pumped through delivery catheter 48 or deployment catheter 16 to clear the field within imaging hood 12. As shown in FIG. 3B, the articulatable delivery catheter 48 may be articulated within the imaging hood to obtain a belter image of tissue adjacent to the imaging hood 12. Moreover, articulatable delivery catheter 48 may be articulated to direct an instrument or tool passed, through the catheter 48, as described in detail below, to specific areas of tissue imaged through imaging hood 12 without having to reposition deployment catheter 16 and re-clear the imaging field within hood 12.

Alternatively, rather than passing an articulatable delivery catheter 48 through the deployment catheter 16, a distal portion of the deployment catheter 16 itself may comprise a distal end 49 which is articulatable within imaging hood 12, as shown in FIG. 3C. Directed imaging, instrument delivery, etc., may be accomplished directly through one or more lumens within deployment catheter 16 to specific regions of the underlying tissue imaged within imaging hood 12.

Visualization within the imaging hood 12 may be accomplished through an imaging lumen 20 defined through deployment catheter 16, as described above. In such a configuration, visualization is available in a straight-line manner, i.e., images are generated from the field distally along a longitudinal axis defined by the deployment catheter 16. Alternatively or additionally, an articulatable imaging assembly having a pivotable support member 50 may be connected to, mounted to, or otherwise passed through deployment catheter 16 to provide for visualization off-axis relative to the longitudinal axis defined by deployment catheter 16, as shown in FIG. 4A. Support member 50 may have an imaging element 52, e.g., a CCD or CMOS imager or optical fiber, attached at its distal end with its proximal end connected to deployment catheter 16 via a pivoting connection 54.

If one or more optical fibers are utilized for imaging, the optical fibers 58 may be passed through deployment catheter 16, as shown in the cross-section of FIG. 4B, and routed through the support member 50. The use of optical fibers 58 may provide for increased diameter sizes of the one or several lumens 56 through deployment catheter 16 for the passage of diagnostic and/or therapeutic tools therethrough. Alternatively, electronic chips, such as a charge coupled device (CCD) or a CMOS imager, which are typically known, may be utilized in place of the optical fibers 58, in which case the electronic imager may be positioned in the distal portion of the deployment, catheter 16 with electric wires being routed proximally through the deployment catheter 16. Alternatively, the electronic imagers may be wirelessly coupled to a receiver for the wireless transmission of images. Additional optical fibers or light emitting diodes (LEDs) can be used to provide lighting for the image or operative theater, as described below in further detail. Support member 50 may be pivoted via connection 54 such that the member 50 can be positioned in a low-profile configuration within channel or groove 60 defined in a distal portion of catheter 16, as shown in the cross-section of FIG. 4C. During intravascular delivery of deployment catheter 16 through the patient body, support member 50 can be positioned within channel or groove 60 with imaging hood 12 also in its low-profile configuration. During visualization, imaging hood 12 may be expanded into its deployed configuration and support member 50 may be deployed into its off-axis configuration for imaging the tissue adjacent to hood 12, as in FIG. 4A. Other configurations for support member 50 for off-axis visualization may be utilized, as desired.

FIG. 4D show s a partial cross-sectional view of an example where one or more optical fiber bundles 62 may be positioned within the catheter and within imaging hood 12 to provide direct in-line imaging of the open area within hood 12. FIG. 4E shows another example where an imaging element 64 (e.g., CCD or CMOS electronic imager) may be placed along an interior surface of imaging hood 12 to provide imaging of the open area such that the imaging element 64 is off-axis relative to a longitudinal axis of the hood 12. The off-axis position of element 64 may provide for direct visualization and uninhibited access by instruments from the catheter to the underlying tissue during treatment.

FIG. 5 shows an illustrative cross-sectional view of a heart H having tissue regions of interest being viewed via an imaging assembly 10. In this example, delivery catheter assembly 70 may be introduced percutaneously into the patient's vasculature and advanced through the superior vena cava SVC and into the right atrium RA. The delivery catheter or sheath 72 may be articulated through the atrial septum AS and into the left atrium LA for viewing or treating the tissue, e.g., the annulus A, surrounding the mitral valve MV. As shown, deployment catheter 16 and imaging hood 12 may be advanced out of delivery catheter 72 and brought into contact or in proximity to the tissue region of interest. In other examples, delivery catheter assembly 70 may be advanced through the inferior vena cava IVC, if so desired. Moreover, other regions of the heart H, e.g., the right ventricle RV or left ventricle LV, may also be accessed and imaged or treated by imaging assembly 10.

In accessing regions of the heart H or other parts of the body, the delivery catheter or sheath 14 may comprise a conventional intra-vascular catheter or an endoluminal delivery device. Alternatively, robotically-controlled delivery catheters may also be optionally utilized with the imaging assembly described herein, in which ease a computer-control let 74 may be used to control the articulation and positioning of the delivery catheter 14. An example of a robotically-controlled delivery catheter which may be utilized is described in further detail in US Pat. Pub. 2002/0087169 A1 to Brock et al. entitled “Flexible Instrument”, which is incorporated herein by reference in its entirety. Other robotically-controlled delivery catheters manufactured by Hansen Medical, inc. (Mountain View, Calif.) may also be utilized with the delivery catheter 14.

To facilitate stabilization of the deployment catheter 16 during a procedure, one or more inflatable balloons or anchors 76 may be positioned along the length of catheter 16, as shown in FIG. 6A. For example, when utilizing a transseptal approach across the atrial septum AS into the left atrium LA, the inflatable balloons 76 may be inflated from a low-profile into their expanded configuration to temporarily anchor or stabilize the catheter 16 position relative to the heart H. FIG. 6B shows a first balloon 78 inflated while FIG. 6C also shows a second balloon 80 inflated proximal to the first balloon 78. In such a configuration, the septal wall AS may be wedged or sandwiched between the balloons 78, 80 to temporarily stabilize the catheter 16 and imaging hood 12. A single balloon 78 or both balloons 78, 80 may be used. Other alternatives may utilize expandable mesh members, malecots, or any other temporary expandable structure. After a procedure has been accomplished, the balloon assembly 76 may be deflated or re-configured into a low-profile for removal of the deployment catheter 16.

To further stabilize a position of the imaging hood 12 relative to a tissue surface to be imaged, various anchoring mechanisms may be optionally employed for temporarily holding the imaging hood 12 against the tissue. Such anchoring mechanisms may be particularly useful for imaging tissue which is subject to movement, e.g., when imaging tissue within the chambers of a beating heart. A tool delivery catheter 82 having at least one instrument lumen and an optional visualization lumen may be delivered through deployment catheter 16 and into an expanded imaging hood 12. As the imaging hood 12 is brought into contact against, a tissue surface T to be examined, anchoring mechanisms such as a helical tissue piercing device 84 may be passed through the tool delivery catheter 82, as shown in FIG. 7A, and into imaging hood 12.

The helical tissue engaging device 84 may be torqued from its proximal end outside the patient body to temporarily anchor itself into the underlying tissue surface T. Once embedded within the tissue T, the helical tissue engaging device 84 may be pulled proximally relative to deployment catheter 16 while the deployment catheter 16 and imaging hood 12 are pushed distally, as indicated by the arrows in FIG. 7B, to gently force the contact edge or lip 22 of imaging hood against the tissue T. The positioning of the tissue engaging device 84 may be locked temporarily relative to the deployment catheter 16 to ensure secure positioning of the imaging hood 12 during a diagnostic or therapeutic procedure within the imaging hood 12. After a procedure, tissue engaging device 84 may be disengaged from the tissue by torquing its proximal end in the opposite direction to remove the anchor form the tissue T and the deployment catheter 16 may be repositioned to another region of tissue where the anchoring process may be repeated or removed from the patient body. The tissue engaging device 84 may also be constructed from other known tissue engaging devices such as vacuum-assisted engagement or grasper-assisted engagement tools, among others.

Although a helical anchor 84 is shown, this is intended to be illustrative and other types of temporary anchors may be utilized, e.g., hooked or barbed anchors, graspers, etc. Moreover, the tool delivery catheter 82 may be omitted entirely and the anchoring device may be delivered directly through a lumen defined through the deployment catheter 16.

In another variation where the tool delivery catheter 82 may be omitted entirely to temporarily anchor imaging hood 12, FIG. 7C shows an imaging hood 12 having one or more tubular support members 86, e.g., four support members 86 as shown, integrated with the imaging hood 12. The tubular support members 86 may define lumens therethrough each having helical tissue engaging devices 88 positioned within. When an expanded imaging hood 12 is to be temporarily anchored to the tissue, the helical tissue engaging devices 88 may be urged distally to extend from imaging hood 12 and each may be torqued from its proximal end to engage the underlying tissue T. Each of the helical tissue engaging devices 88 may be advanced through the length of deployment catheter 16 or they may be positioned within tubular support members 86 during the delivery and deployment of imaging hood 12. Once the procedure within imaging hood 12 is finished, each of the tissue engaging devices 88 may be disengaged from the tissue and the imaging hood 12 may be repositioned to another region of tissue or removed from the patient body.

An illustrative example is shown in FIG. 8A of a tissue imaging assembly connected to a fluid delivery system 90 and to an optional processor 98 and image recorder and/or viewer 100. The fluid delivery system 90 may generally comprise a pump 92 and an optional valve 94 for controlling the How rate of the fluid into the system. A fluid reservoir 96, fluidly connected to pump 92, may hold the fluid to be pumped through imaging hood 12. An optional central processing unit or processor 98 may be in electrical communication with fluid delivery system 90 for controlling flow parameters such as the flow rate and/or velocity of the pumped fluid. The processor 98 may also be in electrical communication with an image recorder and/or viewer 100 for directly viewing the images of tissue received from within imaging hood 12. Imager recorder and/or viewer 100 may also be used not only to record the image but also the location of the viewed tissue region, if so desired.

Optionally, processor 98 may also be utilized to coordinate the fluid flow and the image capture. For instance, processor 98 may be programmed to provide for fluid flow from reservoir 96 until the tissue area has been displaced of blood to obtain a clear image. Once the image has been determined to be sufficiently clear, either visually by a practitioner or by computer, an image of the tissue may be captured automatically by recorder 100 and pump 92 may be automatically stopped or slowed by processor 98 to cease the fluid flow into the patient. Other variations for fluid delivery and image capture are, of course, possible and the aforementioned configuration is intended only to be illustrative and not limiting.

FIG. 8B shows a further illustration of a hand-held variation of the fluid delivery and tissue manipulation system 110. In this variation, system 110 may have a housing or handle assembly 112 which can be held or manipulated by the physician from outside the patient body. The fluid reservoir 114, shown in this variation as a syringe, can be fluidly coupled to the handle assembly 112 and actuated via a pumping mechanism 116, e.g., lead screw. Fluid reservoir 114 may be a simple reservoir separated from the handle assembly 112 and fluidly coupled to handle assembly 112 via one or more tubes. The fluid flow rate and other mechanisms may be metered by the electronic controller 118.

Deployment of imaging hood 12 may be actuated by a hood deployment switch 120 located on the handle assembly 112 while dispensation of the fluid from reservoir 114 may be actuated by a fluid deployment switch 122, which can be electrically coupled to the controller 118. Controller 118 may also be electrically coupled to a wired or wireless antenna 124 optionally integrated with the handle assembly 112, as shown in the figure. The wireless antenna 124 can be used to wirelessly transmit images captured from the imaging hood 12 to a receiver, e.g., via Bluetooth® wireless technology (Bluetooth SIG, Inc., Bellevue, Wash.), RF, etc., for viewing on a monitor 128 or for recording for later viewing.

Articulation control of the deployment catheter 16, or a delivery catheter or sheath 14 through which the deployment catheter 16 may be delivered, may be accomplished by computer control, as described above, in which case an additional controller may be utilized with handle assembly 112. In the case of manual articulation, handle assembly 112 may incorporate one or more articulation controls 126 for manual manipulation of the position of deployment catheter 16. Handle assembly 112 may also define one or more instrument ports 130 through which a number of intravascular tools may be passed for tissue manipulation and treatment within imaging hood 12, as described further below. Furthermore, in certain procedures, fluid or debris may be sucked into imaging hood 12 for evacuation from the patient body by optionally fluidly coupling a suction pump 132 to handle assembly 112 or directly to deployment catheter 16.

As described above, fluid may be pumped continuously into imaging hood 12 to provide for clear viewing of the underlying tissue. Alternatively, fluid may be pumped temporarily or sporadically only until a clear view of the tissue is available to be imaged and recorded, at which point the fluid flow may cease and the blood may be allowed to seep or flow back into imaging hood 12. FIGS. 9A to 9C illustrate an example of capturing several images of the tissue at multiple regions. Deployment catheter 16 may be desirably positioned and imaging hood 12 deployed and brought into position against a region of tissue to be imaged, in this example the tissue surrounding a mitral valve MV within the left atrium of a patient's heart. The imaging hood 12 may be optionally anchored to the tissue, as described above, and then cleared by pumping the imaging fluid into the hood 12. Once sufficiently clear, the tissue may be visualized and the image captured by control electronics 118. The first captured image 140 may be stored and/or transmitted wirelessly 124 to a monitor 128 for viewing by the physician, as shown in FIG. 9A.

The deployment catheter 16 may be then repositioned to an adjacent portion of mitral valve MV, as shown in FIG. 9B, where the process may be repeated to capture a second image 142 for viewing and/or recording. The deployment catheter 16 may again be repositioned to another region of tissue, as shown in FIG. 9C, where a third image 144 may be captured for viewing and/or recording. This procedure may be repeated as many times as necessary for capturing a comprehensive image of the tissue surrounding mitral valve MV, or any other tissue region. When the deployment catheter 16 and imaging hood 12 is repositioned from tissue region to tissue region, the pump may be slopped during positioning and blood or surrounding fluid may be allowed to enter within imaging hood 12 until the tissue is to be imaged, where the imaging hood 12 may be cleared, as above.

As mentioned above, when the imaging hood 12 is cleared, by pumping the imaging fluid within for clearing the blood or other bodily fluid, the fluid may be pumped continuously to maintain the imaging fluid within the hood 12 at a positive pressure or it may be pumped under computer control for slowing or stopping the fluid flow into the hood 12 upon detection of various parameters or until a clear image of the underlying tissue is obtained. The control electronics 118 may also be programmed to coordinate the fluid flow into the imaging hood 12 with various physical parameters to maintain a clear image within imaging hood 12.

One example is shown in FIG. 10A which shows a chart 150 illustrating how fluid pressure within the imaging hood 12 may be coordinated with the surrounding blood pressure. Chart 150 shows the cyclical blood, pressure 156 alternating between diastolic pressure 152 and systolic pressure 154 over time T due to the beating motion of the patient heart. The fluid pressure of the imaging fluid, indicated by plot 160, within imaging hood 12 may be automatically timed to correspond to the blood pressure changes 160 such that an increased pressure is maintained within imaging hood 12 which is consistently above the blood pressure 156 by a slight increase ΔP, as illustrated by the pressure difference at the peak systolic pressure 158. This pressure difference, ΔP, may be maintained within imaging hood 12 over the pressure variance of the surrounding blood pressure to maintain a positive imaging fluid pressure within imaging hood 12 to maintain a clear view of the underlying tissue. One benefit of maintaining a constant ΔP is a constant flow and maintenance of a clear field.

FIG. 10B shows a chart 162 illustrating another variation for maintaining a clear view of the underlying tissue where one or more sensors within the imaging hood 12, as described in further detail below, may be configured to sense pressure changes within the imaging hood 12 and to correspondingly increase the imaging fluid pressure within imaging hood 12. This may result in a time delay, ΔT, as illustrated by the shifted fluid pressure 160 relative to the cycling blood pressure 156, although the time delays ΔT may be negligible in maintaining the clear image of the underlying tissue. Predictive software algorithms can also be used to substantially eliminate this time delay by predicting when the next pressure wave peak will arrive and by increasing the pressure ahead of the pressure wave' s arrival by an amount of time equal to the aforementioned time delay to essentially cancel the time delay out.

The variations in fluid pressure within imaging hood 12 may be accomplished in part due to the nature of imaging hood 12. An inflatable balloon, winch Is conventionally utilized for imaging tissue, may be affected by the surrounding blood pressure changes. On the other hand, an imaging hood 12 retains a constant volume therewithin and is structurally unaffected by the surrounding blood pressure changes, thus allowing for pressure increases therewithin. The material that hood 12 is made from may also contribute to the manner in which the pressure is modulated within this hood 12. A stiffer hood material such as high durometer polyurethane or Nylon, may facilitate the maintaining of an open hood when deployed. On the other hand, a relatively lower durometer or softer material, such as a low durometer PVC or polyurethane, may collapse from the surrounding fluid pressure and may not adequately maintain a deployed or expanded hood.

The imaging hood itself may be formed into any number of configurations and the imaging assembly may also be utilized with any number of therapeutic tools, such as tissue ablation instruments, which may be deployed through the deployment catheter. One particular variation may employ an imaging hood having a tissue anchor deployable therethrough and into a portion of a body lumen such as the pulmonary vein. Once the anchor has been temporarily deployed and secured within the pulmonary vein, the hood and ablation instrument may be articulated around a circumference of the vein ostium or several ostia where the tissue may be ablated in a controlled and consistent manner to electrically isolate the tissue such that a conduction block is created.

Generally, while the imaging hood is moved around the tissue with the anchor deployed and secured distally within the pulmonary vein, the imaging hood may be articulated such that blood flow through the pulmonary vein is unobstructed or uninhibited by the hood. The tissue surrounding the ostium may be visualized via the imaging hood prior to, during, or after the ablation to ensure that the appropriate tissue is suitably ablated for treating conditions such as atrial fibrillation. The distally located anchor which secures a relative position of the imaging hood with respect to the tissue may be maintained until the procedure is completed. After completion, the anchor may be at least partially withdrawn into the imaging hood or reconfigured into a low-profile shape to disengage the tissue and allow the imaging hood to be removed or repositioned in the patient body.

Turning now to FIGS. 11A and 11B, which show respective side and end views of visualization hood 12 placed against and visualizing a portion of the ostium, e.g., the ostium OS_(LS) of the left superior pulmonary vein PV_(LS). Placement and movement of hood 12 about ostium OS_(LS) may be facilitated by the deployment and placement of an anchor within the respective pulmonary vein while tethered to hood 12 or catheter 16. Generally, the anchor situated within the pulmonary vein may be sufficiently open such that the anchor does not obstruct blood flow through the pulmonary vein. Although the examples illustrate placement of the anchors within the left superior pulmonary vein PV_(LS) and ablation or treatment of the respective left superior ostium OS_(LS), this is intended to be illustrative and anchoring within the other pulmonary veins and other vessels and/or treatment of the respective ostia are included within the scope of this disclosure.

In this example, the pulmonary vein anchor may be configured as a helical anchor 170 which is attached, to an anchor member 172, e.g., a guidewire, such that helical anchor 170 may be advanced through delivery catheter 16 in a low-profile configuration and then slowly expanded when, advanced distally out of catheter 16. As helical anchor 170 expands, anchor member 170 may be advanced distally within the pulmonary vein until anchor 170 is expanded into contact against the wall of the pulmonary vein, as shown in FIG. 11A. Alternatively, a deployment sheath may be advanced through a working channel of deployment catheter 16, through hood 12, and distally into the pulmonary vein. When the deployment sheath is desirably situated within the pulmonary vein, helical anchor 170 may be advanced distally and/or the sheath may be retracted proximally to deploy and expand the anchor 170. Anchor 170 is described in further detail below.

With helical anchor 170 secured within the pulmonary vein, hood 12 may be placed into contact against a portion of ostium OS_(LS) by pushing hood 12 along anchor member 172 distally in the direction towards anchor 170 until hood 12 is pressed against the tissue surface. Once pressed against the tissue surface, the transparent purging fluid 28 may be pumped into open area or field 26 to enable direct visualization of the tissue surrounding ostium OS_(LS) while surrounded by blood 30.

As previously mentioned unobstructed blood flow 178 may continue through, the pulmonary vein PV_(LS) past anchor 170 because of its non-obstructive configuration while the tissue underlying hood 12 is visualized by imaging element 176, e.g., CCD, CMOS, or optical fiber, etc., positioned upon or along hood 12 or within catheter 16. Unlike an anchoring balloon where an entire inflated balloon potentially blocks the pulmonary vein and deprives the heart of oxygenated blood from the pulmonary vein, anchor 170 is able to be secured against the vessel wall without blocking the vessel lumen. Unobstructed blood flow is further facilitated by positioning the hood 12 laterally relative to the ostium OS_(LS) such that the vessel opening remains minimally obstructed or completely unobstructed, as shown in FIG. 11B.

By maintaining contact between hood 12 and the tissue surrounding OS_(LS), an instrument such as ablation probe 174 may be advanced within hood 12 and placed into contact against or in proximity to the underlying tissue which maybe ablated while under direct visualization via imaging element 176. Ablation, probe 174 may ablate the tissue immediately underlying hood 12 and hood 12 may then be repositioned over an adjacent region of tissue to be ablated where the process may be repeated. Alternatively, hood 12 may be moved circumferentially about ostium OS_(LS) while ablating the underlying tissue in a continuous manner. In either case, anchor member 172 may act as a guide to ensure that hood 12 stays or tracks circumferentially around ostium OS_(LS) during ablation. As shown in the side and end views of FIGS. 12A and 12B, respectively, an example of how hood 12 may be moved around the ostium OS_(LS) during ablation is illustrated where hood 12 is moved in a counter-clockwise motion relative to ostium OS_(LS). Alternatively, hood 12 may be moved in a clockwise motion as well. By articulating or translating the hood 12 along the plane of the ostium OS_(LS) at an angle away from the pulmonary vein PV_(LS), hood 12 may continue to capture a portion of the ostium OS_(LS) as anchor 170 and anchor member 172 may confine the motion of the hood 12 to the circumference -of the ostium OS_(LS).

As further illustrated in FIG. 12B, a number of discrete lesions 182 may be formed upon the tissue underlying hood 12. Repositioning of hood 12 adjacent to the ablated tissue may allow for the creation of another discrete lesion 182 which may be overlapped upon one another such that, a single continuous lesion 180 is collectively formed. This process may be repeated until the desired circumference of tissue is ablated. Alternatively, the continuous lesion 180 may be formed while simultaneously ablating and moving hood 12 and ablation probe 174 around ostium OS_(LS) such that a single continuous line of tissue is ablated. In either case, the underlying tissue being ablated may be viewed under direct visualization from imaging element 176.

FIGS. 13A to 13C illustrate hood 12 and ablation probe 174 being constrained by anchor member 172 coupled to anchor 170 to follow a circumferential path around the ostium OS_(LS) as hood 12 is articulated via catheter 16. As previously mentioned, although hood 12 is illustrated following a counter-clockwise direction about OS_(LS), hood 12 may be articulated to follow a clockwise direction as well. Moreover, FIGS. 13A and 13B illustrate ablation probe 174 being used to create a series of overlapping discrete lesions 182 to create a continuous lesion 180 such that the entire circumference of tissue surrounding ostium OS_(LS) is ablated to completely electrically isolate the ostium OS_(LS). FIG. 13C illustrates the resulting lesion 180 formed by the ablated tissue once anchor 170 and anchor member 172 have been withdrawn and hood 12 has been removed from the ostium OS_(LS). Although lesion 180 is illustrated as encircling the entire circumference of ostium OS_(LS) one or more discrete portions of the surrounding tissue may be ablated instead depending upon the desired results. Moreover, the circumference, or portions of the circumference, of ostium OS_(LS) may be ablated while under direct, visualization within hood 12 while allowing for obstructed blood flow 178 from the respective pulmonary vein.

As described above, helical anchor 170 may be advanced through catheter 16 and through hood 12 in a low-profile configuration while constrained either by a delivery lumen of catheter 16 or by an optional anchor sheath 190 advanced through the delivery lumen, while constraining anchor 170. FIG. 14A shows an example of an optional anchor sheath 190 having helical anchor 170 ex lending from anchor member 172 constrained within anchor lumen 192 in its low-profile configuration. When helical anchor 170 is to be deployed from anchor lumen 192, anchor 170 may be advanced relative to sheath 190 and/or sheath 190 may be retracted relative to anchor 170 such that helical anchor 170 may be extended beyond lumen 192 such that anchor 170 is unconstrained and allowed to expand radially, as illustrated in FIG. 14B,

Once deployed within the vessel lumen, such as the pulmonary vein PV_(LS), as shown in the partial cross-sectional view of FIG. 14C, helical anchor 170 may be expanded or reconfigured such that, anchor 170 does not obstruct blood flow 178 within the pulmonary vein PV_(LS). The expanded anchor 170 may provide engagement and orientation for hood 12 relative to the underlying tissue surrounding the ostium to conduct direct visualization and ablation of the tissue surrounding the ostium OS_(LS), as described above. The anchor 170 may secure itself to the vessel wall by expanding laterally, e.g., perpendicularly relative to a longitudinal axis of the anchor 170, and applying a radial outward force upon the tissue walls of the vessel. Fractional contact between the helical anchor 170 and the tissue surface may provide additional force to secure the anchor 170 in place. The helical anchor 170 can be formed from a wire made from a variety of materials, e.g., shape memory alloys such as Nitinol. When the helical anchor 170 is retracted back into sheath 190, the anchor 170 may return to its original low-profile shape for repositioning or tor removal from the patient.

FIGS. 15A and 15B show partial cross-sectional views of another variation of the anchor for placement within the pulmonary vein where the anchor is configured as a reconfigurable basket anchor 200 which is deliverable in its low-profile configuration where basket anchor 200 is constrained within lumen 192 of sheath 190, as shown in FIG. 15A, and deployable into an expanded or extended basket configuration, as shown in FIG. 15B.

Basket anchor 200 may be formed to have several reconfigurable basket arms or members 206 which are each connected at a distal connection 202 and at a proximal connection 204. Basket anchor 200 may extend distally from anchor member 208 such that distal movement of anchor member 208 (and/or proximal retraction of sheath 190) may urge basket anchor 200 out of lumen 192 where, basket arms or members 206 may expand laterally into its basket configuration, e.g., where arms or members 206 reconfigure perpendicularly relative to the axis of the basket 200, and into contact against the vessel walls, as shown in FIG. 15C. Fractional contact between arms or members 206 and the tissue surface in contact provides additional force to secure the anchor 200 in place. Even in its expanded configuration, basket anchor 200 may provide an open pathway for blood flow 178 to continue relatively unobstructed between the arms or members 206 and through the vessel.

As above, basket anchor 200 can be fabricated from shape memory alloy tubing such as Nitinol or from metal wires or ribbons such as stainless steel, titanium, etc. When retracted proximally back into sheath 190, the basket anchor 200 may return to its original low-profile shape for repositioning within the same or different vessel or for removal from the patient.

In yet another variation, FIGS. 16A and 16B show partial cross-sectional side views of an anchor configured as a mesh anchor 210. This mesh anchor 210 variation may anchor itself to the walls of the pulmonary vein PV_(LS) by expanding laterally into a basket-like frame, e.g., perpendicularly relative to the longitudinal axis of the anchor 210, and applying a radial outward force on the walls of the vessel. The anchor 210 may generally comprise multiple wire or ribbon members 216 which are woven, interwoven, or interlaced with respect to one another to form the mesh which is connected at a distal connection 212 and a proximal connection 214 and attached, coupled, or otherwise extending from anchor member 218. The wire or ribbon members 216 can be formed from shape memory alloy such as Nitinol or from a polymeric of plastic material such as PET. When compressed into a low-profile cylindrical configuration and loaded in the lumen 192 of sheath 190, as shown in FIG. 16A, mesh, anchor 210 may return to its expanded configuration by having wire or ribbon members 216 expanded into the basket-like structure when deployed from sheath 190, as shown in FIG. 16B. Moreover, when deployed and secured against the vessel wall, as shown in FIG. 16C, blood flow 178 may continue relatively unobstructed by flowing between the members 216.

In yet another variation, the pulmonary vein anchor may be configured as a balloon anchor assembly 220 having several balloon members which are inflatable into a staggered pattern for securement within the vessel. As shown in FIG. 17A, the staggered balloon assembly 220 may be advanced at least partially within, e.g., the pulmonary vein PV_(LS) while in a deflated or low-profile configuration. Once desirably positioned, staggered balloon anchor assembly 220 may be infused with a gas (such as nitrogen) or fluid (such as saline) via inflation lumen 228 to expand several balloons positioned in a staggered pattern along the inflation lumen 228. In this example, first offset balloon 222 may be positioned distally along lumen 228 while second offset balloon 224 may be positioned proximally and in an offset position relative to first offset balloon 222. A third offset balloon 226 may be positioned proximally of second balloon 224 such that it is offset with respect to second balloon 224 and/or first balloon 222, as illustrated in FIG. 17B. Although, three balloon members are shown in this example, other variations may utilize two balloons or more than three balloons. Moreover, rather than having balloon members offset with respect to one another, balloon members may be configured into other shapes which still allow for blood flow through the vessel, e.g., one or more toroidal shaped balloon members.

Once the balloon assembly 220 is inflated and secured within the vessel, blood flow 178 may continue through the pulmonary vein PV_(LS) such that the blood is able to meander in an offset flow pattern 230 past the staggered balloons. The staggered balloons can be made from a variety of materials typically utilized for biocompatible inflatable balloons, e.g., medical grade elastomers such as C-flex, chronoprene, silicone or polyurethane, etc.

In yet another variation, rather than utilizing a separately deployable anchor for placement within the vessel lumen. FIGS. 18A and 18B show a variation of the tissue visualization catheter having a reconfigurable flap 240 which is configured to pivot about the contact hp or edge 22 of the hood 12. In its low-profile configuration, flap 240 may remain folded inwardly along the inner wall of the hood 12. An inflation lumen 246 may extend from the catheter 16 along or within the wall of the hood 12 and terminate proximal to the flap 240 at an inflatable member or balloon 242 positioned between flap 241 and hood 12. Balloon 242 may be fabricated from a variety of materials, such as C-flex, chronoprene, polyurethane, etc. and it may be separately attached to hood 12 or it may optionally be integrated with the material of hood 12. Upon injecting a fluid or gas through lumen 246, balloon 242 may be inflated such that flap 240 is lifted or rotated in the direction 244 from its low-profile position along the inner wall of hood 12, as shown in FIG. 18A, into its extended position, as shown in FIG. 18B. When the flap 240 is lifted passed an angle of approximately 25° or more relative to the lining of hood 12, the flap 240 may be configured to flip open into its extended configuration. FIGS. 19A and 19B illustrate perspective views of flap 240 in its low-profile configuration and its extended configuration, respectively, corresponding to FIGS. 18A and 18B above.

In use, flap 240 in its extended position may act as a guide for the hood 12 to trace the ostium OS_(LS) to ensure that hood 12 moves along the circumference of the ostium OS_(LS). As illustrated in the side view of FIG. 20, hood 12 may be positioned in proximity to the vessel and ostium to be treated. In this example, flap 240 may be extended and hood 12 may be placed laterally relative to the vessel such that flap 240 is positioned at least partially along the opening of the pulmonary vein PV_(LS) and only a small portion of the vessel opening is covered such that blood flow 178 through the vessel may continue unobstructed by the hood 12. In this position, hood 12 is desirably positioned upon the ostium OS_(LS) to allow the hood 12 and ablation probe 174 positioned there within to treat the underlying tissue while under direct visualization through the hood 12.

As illustrated in FIGS. 21A to 21C, with extended flap 240 positioned at least partially within the vessel and acting as a guide, hood 12 may be moved circumferentially via catheter 16, or at least partially, around the ostium OS_(LS) to create one or more discrete lesions 182 or a continuous lesion 180. FIG. 21C illustrates the resulting lesion 180 created circumferentially about the ostium OS_(LS) to electrically isolate the tissue region.

In other variations for creating lesions about the ostium of a vessel, FIG. 22 shows a perspective view of an example of a device utilizing a side port 250 defined along the catheter 16 proximal to the hood 12 for intravascular creating lesions around multiple ostia. Although the anchor configuration is illustrated with helical anchor 170 attached to anchor member 172 extending through port 250, other anchors which are non-obstructing to the blood flow through the vessel may be utilized, such as basket anchors, mesh anchors, staggered, balloons, etc. An anchor deployed from the side port 250 of the catheter 16 may provide hood 12 additional degrees-of-freedom of controlled motion within the chamber (such as the left atrium LA) of the heart.

In use, anchor 170 may be deployed through port 250 proximal to the hood 12 and advanced into, e.g., pulmonary vein PV_(LS), by advancing anchor member 172 (indicated by the direction of advancement 252) where it may be secured within the vessel without obstructing blood flow therethrough, as shown in the perspective view of FIG. 23A. Hood 12 may then be articulated via catheter 16 (indicated by the direction of articulation 254) while tethered and guided by anchor member 172 to facilitate the ablation process by allowing hood 12 to be maneuvered especially when isolating two or more ostia, e.g., left superior ostium OS_(LS) and left inferior ostium OS_(LS), within one continuous circumferential lesion, as shown in FIG. 23B. Other tissue regions may be ablated in the same manner to create lesion patterns around the various ostia or around all four ostia within the left atrium LA. Moreover, the side ported anchor may also provide additional apposition strength for the hood 12 to engage the ablated tissue surface when the anchor 170 is pulled from the side port 250.

Another variation may include having two or more side ports near or at the distal end of the catheter 16 proximal to hood 12, with each side port deploying a respective anchor. When one anchor secures itself to the right superior/inferior pulmonary vein while the other pulmonary vein anchor secures itself within the left superior/inferior PV, navigation around all four pulmonary vein ostia and apposition to target tissue surface in the vicinity of the four pulmonary vein ostia can be achieved. This can be made so by pulling on each of the two anchor members with varying tension and by rotating the hood 12 about the axis of the anchor members. Both linear lesions connecting the pulmonary veins and circumferential lesions around the respective ostia can be formed by maneuvering the hood 12 accordingly.

The applications of the disclosed invention discussed above are not limited to certain treatments or regions of the body, but may include any number of other treatments and areas of the body. Modification of the above-described methods and devices for carrying out the invention, and variations of aspects of the invention that are obvious to those of skill in the arts are intended to be within the scope of this disclosure. Moreover, various combinations of aspects between examples are also contemplated and are considered to be within the scope of this disclosure as well. 

What is claimed is:
 1. A method of treating tissue surrounding a vessel opening, comprising: intravascularly securing an anchor extending from an anchor member at least partially within a vessel lumen such that blood flows unobstructed through or past the anchor; adjusting a distance of the anchor member between the anchor and a barrier or membrane projecting distally from a deployment catheter such that an open area defined by the barrier or membrane is placed against or adjacent to a portion of the tissue surrounding the vessel opening; displacing blood with a transparent fluid from the open area; and treating the tissue while visualizing through the transparent fluid.
 2. The method of claim 15 wherein intravascularly securing comprises advancing the anchor within a lumen of a pulmonary vein.
 3. The method of claim 15 wherein intravascularly securing comprises expanding the anchor from a low-profile shape to an expanded shape.
 4. The method of claim 15 wherein intravascularly securing comprises expanding the anchor having a helical shape.
 5. The method of claim 15 wherein intravascularly securing comprises expanding the anchor having a basket shape.
 6. The method of claim 15 wherein intravascularly securing comprises expanding the anchor having a mesh shape.
 7. The method of claim 15 wherein adjusting comprises tensioning the anchor member extending through the open area of the barrier or membrane.
 8. The method of claim 15 wherein adjusting comprises tensioning the anchor member extending through an opening defined along the catheter proximal to the barrier or membrane.
 9. The method of claim 15 wherein treating comprises ablating the tissue with an ablation probe advanced into the open area.
 10. The method of claim 15 wherein treating comprises circumferentially ablating the tissue surrounding the vessel opening.
 11. The method of claim 24 wherein circumferentially ablating comprises ablating the tissue in a continuous line while visualizing through the transparent fluid.
 12. The method of claim 24 wherein circumferentially ablating comprises ablating the tissue along discrete lesions which overlap one another surrounding the vessel opening.
 13. A method of ablating tissue surrounding a vessel opening, comprising: positioning an anchor at least partially within a vessel lumen, wherein the anchor comprises an open structure which allows unobstructed blood flow through or past the anchor; positioning a barrier or membrane projecting distally from a deployment catheter such that an open area defined by the barrier or membrane is placed against or adjacent to a portion of the tissue surrounding the vessel opening; purging blood with a transparent fluid from the open area such that the portion of tissue is visualized through the transparent fluid; and adjusting a position of the barrier or membrane relative to the vessel opening such that the catheter remains tethered to the anchor.
 14. The method of claim 27 wherein positioning an anchor comprises advancing the anchor within a lumen of a pulmonary vein.
 15. The method of claim 27 wherein positioning a barrier or membrane comprises tensioning an anchor member connected to the anchor and extending through the open area of the barrier or membrane.
 16. The method of claim 27 wherein adjusting a position comprises circumscribing tissue surrounding the vessel opening while tethered to the anchor.
 17. The method of claim 30 wherein circumscribing tissue further comprises visualizing the tissue through the transparent fluid while adjusting the position of the barrier or membrane.
 18. The method of claim 27 further comprising treating the tissue visualized within the open area.
 19. The method of claim 32 wherein treating comprises ablating the tissue visualized within the open area.
 20. The method of claim 33 wherein treating comprises circumferentially ablating the tissue surrounding the vessel opening.
 21. The method of claim 33 wherein treating comprises circumferentially ablating the tissue in a continuous line while visualizing through the transparent fluid.
 22. The method of claim 33 wherein circumferentially ablating comprises ablating the tissue along discrete lesions which overlap one another surrounding the vessel opening. 